1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/uio/uio_pdrv_genirq.c
4 *
5 * Userspace I/O platform driver with generic IRQ handling code.
6 *
7 * Copyright (C) 2008 Magnus Damm
8 *
9 * Based on uio_pdrv.c by Uwe Kleine-Koenig,
10 * Copyright (C) 2008 by Digi International Inc.
11 * All rights reserved.
12 */
13
14#include <linux/platform_device.h>
15#include <linux/uio_driver.h>
16#include <linux/spinlock.h>
17#include <linux/bitops.h>
18#include <linux/module.h>
19#include <linux/interrupt.h>
20#include <linux/stringify.h>
21#include <linux/pm_runtime.h>
22#include <linux/slab.h>
23#include <linux/irq.h>
24
25#include <linux/of.h>
26#include <linux/mod_devicetable.h>
27#include <linux/property.h>
28
29#define DRIVER_NAME "uio_pdrv_genirq"
30
31struct uio_pdrv_genirq_platdata {
32 struct uio_info *uioinfo;
33 spinlock_t lock;
34 unsigned long flags;
35 struct platform_device *pdev;
36};
37
38/* Bits in uio_pdrv_genirq_platdata.flags */
39enum {
40 UIO_IRQ_DISABLED = 0,
41};
42
43static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
44{
45 struct uio_pdrv_genirq_platdata *priv = info->priv;
46
47 /* Wait until the Runtime PM code has woken up the device */
48 pm_runtime_get_sync(dev: &priv->pdev->dev);
49 return 0;
50}
51
52static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
53{
54 struct uio_pdrv_genirq_platdata *priv = info->priv;
55
56 /* Tell the Runtime PM code that the device has become idle */
57 pm_runtime_put_sync(dev: &priv->pdev->dev);
58 return 0;
59}
60
61static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
62{
63 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
64
65 /* Just disable the interrupt in the interrupt controller, and
66 * remember the state so we can allow user space to enable it later.
67 */
68
69 spin_lock(lock: &priv->lock);
70 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
71 disable_irq_nosync(irq);
72 spin_unlock(lock: &priv->lock);
73
74 return IRQ_HANDLED;
75}
76
77static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
78{
79 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
80 unsigned long flags;
81
82 /* Allow user space to enable and disable the interrupt
83 * in the interrupt controller, but keep track of the
84 * state to prevent per-irq depth damage.
85 *
86 * Serialize this operation to support multiple tasks and concurrency
87 * with irq handler on SMP systems.
88 */
89
90 spin_lock_irqsave(&priv->lock, flags);
91 if (irq_on) {
92 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
93 enable_irq(irq: dev_info->irq);
94 } else {
95 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
96 disable_irq_nosync(irq: dev_info->irq);
97 }
98 spin_unlock_irqrestore(lock: &priv->lock, flags);
99
100 return 0;
101}
102
103static void uio_pdrv_genirq_cleanup(void *data)
104{
105 struct device *dev = data;
106
107 pm_runtime_disable(dev);
108}
109
110static int uio_pdrv_genirq_probe(struct platform_device *pdev)
111{
112 struct uio_info *uioinfo = dev_get_platdata(dev: &pdev->dev);
113 struct fwnode_handle *node = dev_fwnode(&pdev->dev);
114 struct uio_pdrv_genirq_platdata *priv;
115 struct uio_mem *uiomem;
116 int ret = -EINVAL;
117 int i;
118
119 if (node) {
120 const char *name;
121
122 /* alloc uioinfo for one device */
123 uioinfo = devm_kzalloc(dev: &pdev->dev, size: sizeof(*uioinfo),
124 GFP_KERNEL);
125 if (!uioinfo) {
126 dev_err(&pdev->dev, "unable to kmalloc\n");
127 return -ENOMEM;
128 }
129
130 if (!device_property_read_string(dev: &pdev->dev, propname: "linux,uio-name", val: &name))
131 uioinfo->name = devm_kstrdup(dev: &pdev->dev, s: name, GFP_KERNEL);
132 else
133 uioinfo->name = devm_kasprintf(dev: &pdev->dev, GFP_KERNEL,
134 fmt: "%pfwP", node);
135
136 uioinfo->version = "devicetree";
137 /* Multiple IRQs are not supported */
138 }
139
140 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
141 dev_err(&pdev->dev, "missing platform_data\n");
142 return ret;
143 }
144
145 if (uioinfo->handler || uioinfo->irqcontrol ||
146 uioinfo->irq_flags & IRQF_SHARED) {
147 dev_err(&pdev->dev, "interrupt configuration error\n");
148 return ret;
149 }
150
151 priv = devm_kzalloc(dev: &pdev->dev, size: sizeof(*priv), GFP_KERNEL);
152 if (!priv) {
153 dev_err(&pdev->dev, "unable to kmalloc\n");
154 return -ENOMEM;
155 }
156
157 priv->uioinfo = uioinfo;
158 spin_lock_init(&priv->lock);
159 priv->flags = 0; /* interrupt is enabled to begin with */
160 priv->pdev = pdev;
161
162 if (!uioinfo->irq) {
163 ret = platform_get_irq_optional(pdev, 0);
164 uioinfo->irq = ret;
165 if (ret == -ENXIO)
166 uioinfo->irq = UIO_IRQ_NONE;
167 else if (ret == -EPROBE_DEFER)
168 return ret;
169 else if (ret < 0) {
170 dev_err(&pdev->dev, "failed to get IRQ\n");
171 return ret;
172 }
173 }
174
175 if (uioinfo->irq) {
176 /*
177 * If a level interrupt, dont do lazy disable. Otherwise the
178 * irq will fire again since clearing of the actual cause, on
179 * device level, is done in userspace
180 * irqd_is_level_type() isn't used since isn't valid until
181 * irq is configured.
182 */
183 if (irq_get_trigger_type(irq: uioinfo->irq) & IRQ_TYPE_LEVEL_MASK) {
184 dev_dbg(&pdev->dev, "disable lazy unmask\n");
185 irq_set_status_flags(irq: uioinfo->irq, set: IRQ_DISABLE_UNLAZY);
186 }
187 }
188
189 uiomem = &uioinfo->mem[0];
190
191 for (i = 0; i < pdev->num_resources; ++i) {
192 struct resource *r = &pdev->resource[i];
193
194 if (r->flags != IORESOURCE_MEM)
195 continue;
196
197 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
198 dev_warn(&pdev->dev, "device has more than "
199 __stringify(MAX_UIO_MAPS)
200 " I/O memory resources.\n");
201 break;
202 }
203
204 uiomem->memtype = UIO_MEM_PHYS;
205 uiomem->addr = r->start & PAGE_MASK;
206 uiomem->offs = r->start & ~PAGE_MASK;
207 uiomem->size = (uiomem->offs + resource_size(res: r)
208 + PAGE_SIZE - 1) & PAGE_MASK;
209 uiomem->name = r->name;
210 ++uiomem;
211 }
212
213 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
214 uiomem->size = 0;
215 ++uiomem;
216 }
217
218 /* This driver requires no hardware specific kernel code to handle
219 * interrupts. Instead, the interrupt handler simply disables the
220 * interrupt in the interrupt controller. User space is responsible
221 * for performing hardware specific acknowledge and re-enabling of
222 * the interrupt in the interrupt controller.
223 *
224 * Interrupt sharing is not supported.
225 */
226
227 uioinfo->handler = uio_pdrv_genirq_handler;
228 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
229 uioinfo->open = uio_pdrv_genirq_open;
230 uioinfo->release = uio_pdrv_genirq_release;
231 uioinfo->priv = priv;
232
233 /* Enable Runtime PM for this device:
234 * The device starts in suspended state to allow the hardware to be
235 * turned off by default. The Runtime PM bus code should power on the
236 * hardware and enable clocks at open().
237 */
238 pm_runtime_enable(dev: &pdev->dev);
239
240 ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
241 &pdev->dev);
242 if (ret)
243 return ret;
244
245 ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
246 if (ret)
247 dev_err(&pdev->dev, "unable to register uio device\n");
248
249 return ret;
250}
251
252static int uio_pdrv_genirq_runtime_nop(struct device *dev)
253{
254 /* Runtime PM callback shared between ->runtime_suspend()
255 * and ->runtime_resume(). Simply returns success.
256 *
257 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
258 * are used at open() and release() time. This allows the
259 * Runtime PM code to turn off power to the device while the
260 * device is unused, ie before open() and after release().
261 *
262 * This Runtime PM callback does not need to save or restore
263 * any registers since user space is responsbile for hardware
264 * register reinitialization after open().
265 */
266 return 0;
267}
268
269static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
270 .runtime_suspend = uio_pdrv_genirq_runtime_nop,
271 .runtime_resume = uio_pdrv_genirq_runtime_nop,
272};
273
274#ifdef CONFIG_OF
275static struct of_device_id uio_of_genirq_match[] = {
276 { /* This is filled with module_parm */ },
277 { /* Sentinel */ },
278};
279MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
280module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
281MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
282#endif
283
284static struct platform_driver uio_pdrv_genirq = {
285 .probe = uio_pdrv_genirq_probe,
286 .driver = {
287 .name = DRIVER_NAME,
288 .pm = &uio_pdrv_genirq_dev_pm_ops,
289 .of_match_table = of_match_ptr(uio_of_genirq_match),
290 },
291};
292
293module_platform_driver(uio_pdrv_genirq);
294
295MODULE_AUTHOR("Magnus Damm");
296MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
297MODULE_LICENSE("GPL v2");
298MODULE_ALIAS("platform:" DRIVER_NAME);
299

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source code of linux/drivers/uio/uio_pdrv_genirq.c